The present invention relates to an apparatus and method for inspecting a circuit board.
In manufacturing processes of a circuit board, after forming circuit wirings on a board, it is required to inspect the presence of disconnection and/or short-circuit in the circuit wirings.
The recent progressive densification in the circuit wirings makes it difficult to assure a sufficient space for arranging two separate inspection pins simultaneously and bringing them into contact with the circuit wirings to be inspected. Thus, a non-contact type inspection technique has been proposed in which electric signals were received without using any pin and contacting the circuit wirings (see Japanese Patent Laid-Open Publication No. Hei 9-264919).
As is shown in FIG. 22, in this non-contact type inspection technique, the disconnection or the like is inspected by bringing a pin into contact with one end of the ends of a circuit wiring to be inspected, placing a sensor conductor at the other end of the circuit wiring in non-contact manner, and then detecting with the sensor conductor a potential variation in the circuit wiring caused by supplying an inspection signal to the pin.
However, the above conventional non-contact type inspection technique allows an operator only to determine whether the circuit wiring is present at a given position on a circuit board, but does not allow the operator to intuitively determine the geometry or shape of the circuit wiring.
The present invention is directed to solve the above problem of the conventional technique. It is therefore an object of the present invention to provide an inspection apparatus and inspection method capable of intuitively inspecting a shape of a circuit wiring.
In order to achieve the above object, according to a first aspect of the present invention, there is provided an inspection apparatus for inspecting a circuit wiring on a circuit board, comprising: supply means for supplying an inspection signal to the circuit wiring; detecting means for detecting potential variation appearing in the circuit wiring in response to the inspection signal, by use of plural sensor elements; and image data generating means for generating an image data representing the shape of the circuit wiring, by use of positional information of the sensor elements which have detected the potential variation.
In the inspection apparatus according to the first aspect of the present invention, the supply means may be adapted to supply the inspection signal to the different circuit wiring at a different timing. The term xe2x80x9cdifference circuit wiringxe2x80x9d herein means the electrically separated part of the circuit wiring, which should not be electrically conducted to the remaining part of the circuit wiring in design.
Further, the inspection apparatus may include selecting means for supplying a select signal to selectively drive a part of the plural sensor elements located in a given region of the circuit board.
In the inspection apparatus according to the first aspect of the present invention, the plural sensor elements may be arranged in a matrix form, and the selecting means may be adapted to input the select signal simultaneously into plural sensor element lines which are formed by the plural sensor elements and each of which is aligned horizontally in one line. In addition, the detecting means may be adapted to simultaneously detect the potential variation appearing in the circuit wiring opposed to the sensor element lines.
In this case, the inspection apparatus may further include timing control means for controlling the timing for inputting the select signal to the sensor element lines, the timing for detecting the potential variation from the sensor element lines, and the timing for supplying the inspection signal to the circuit wiring.
Further, the circuit wiring may include a first circuit wiring and a second circuit wiring. In this case, the selecting means may be adapted to drive all of the sensor elements by sequentially inputting the select signal to the sensor element lines, and the detecting means may be adapted to detect the potential variation from all of the sensor elements in conformity with the timing for inputting the select signal from the selecting means. In addition, when a first set of the sensor element lines capable of detecting the potential variation in the first circuit wiring and a second set of the sensor element lines capable of detecting the potential variation in the second circuit wiring are not overlapped at all, the supply means may be adapted to supply the inspection signal to the first and second circuit wirings within the same frame, where a period in which all of the sensor elements are driven once is defined as one frame. Furthermore, when the first and second sets of the sensor element lines are overlapped each other, the supply means may be adapted to supply the inspection signal to the first and second circuit wirings in different frames.
Otherwise, in case of the circuit wiring including a first circuit wiring and a second circuit wiring, the selecting means may be adapted to drive all of the sensor elements by sequentially inputting the select signal vertically to the sensor element lines, and the detecting means may be adapted to detect the potential variation from all of the sensor elements in conformity with the timing for inputting the select signal from the selecting means. In this case, when a first set of the sensor element lines capable of detecting the potential variation in the first circuit wiring and a second set of the sensor element lines capable of detecting the potential variation in the second circuit wiring are overlapped each other, the supply means may be adapted to supply the inspection signal to the first and second circuit wirings within the same frame in different timings, where a period in which all of the sensor elements are driven once is defined as one frame.
Furthermore, the timing control means may be adapted to control the timing for inputting the select signal, the timing for detecting the potential variation from the sensor element lines, and the timing for supplying the inspection signal to the circuit wirings, so as to drive the first set of the sensor element lines which are arranged at the interval of n lines and provided for detecting the first circuit wiring, and the second set of the sensor element lines which are arranged differently from the first set of the sensor element lines at the interval of n lines and provided for detecting the second circuit wiring.
Alternatively, the timing control means may be adapted to control the timing for inputting the select signal, the timing for detecting the potential variation from the sensor element lines, and the timing for supplying the inspection signal to the circuit wirings, so as to drive the first set of the sensor element lines which are arranged at odd lines and provided for detecting the first circuit wiring, and the second set of the sensor element lines which are arranged at even lines and provided for detecting the second circuit wiring.
The image data generating means may be adapted to generate the image data representing each shape of the first and second circuit wirings through an image interpolation process.
According to a second aspect of the present invention, there is provided an inspection apparatus for inspecting plural circuit wirings on a circuit board, comprising: supply means for supplying an inspection signal to each of the plural circuit wirings; first and second area type sensors each opposed to the plural circuit wirings to detect potential variation appearing in the plural circuit wirings in response to the inspection signal; and timing control means for controlling the timing for detecting the potential variations by the sensors. In this case, each of the first and second area type sensors includes plural sensor element lines and is adapted to drive the sensor elements corresponding to the entire area of each of the sensor by sequentially driving the sensor element lines vertically, and at least one of the sensor element lines in the second area type sensor is adapted to detect the potential variation in the circuit wiring opposed thereto between the time after one of the plural sensor element lines in the second area type sensor completes the detection of the potential variation in the circuit wiring opposed thereto and the time before another sensor element line subsequently starts the detection of the potential variation in the circuit wiring opposed thereto.
In the inspection apparatus according to the first or second aspect of the present invention, each of the sensor elements may be formed on a monocrystal of semiconductor or a flat plate, and each of the sensor elements may be adapted to operate as a counter electrode capacitively coupled to the circuit wiring. Further, each of the sensor elements may include a passive element detecting the potential variation in the circuit wiring, and a transistor outputting a detected signal, which is output from the passive element, in response to the input of the select signal.
In order to the above object, according to a third aspect of the present invention, there is provided an inspection method for inspecting a circuit wiring on a circuit board, comprising the steps of: supplying an inspection signal to the circuit wirings; detecting potential variations appearing in the circuit wiring in response to the inspection signal, by use of plural sensor elements; and generating an image data representing the shape of the circuit wiring by use of positional information of the sensor elements which have detected the potential variation.